JP2016017827A - Combination balance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control zero adjustment intervals between individual measuring units in a combination balance without sacrificing either the net weight precision or the combination precision.SOLUTION: A plurality of measuring units 8 measure the weights of measurement objects, and an arithmetic control unit 16 performs combination calculation of the weights of measurement objects weighed by the plurality of measuring units 8. The arithmetic control unit 16 automatically accomplishes zero adjustment by measuring for each individual measuring unit the zero point weight value, which is the weight value of the measuring unit at zero point measuring which represents the state in which no measurement object is supplied to any of the measuring units in operation. During the operation of the combination balance, the arithmetic control unit adjusts the interval from the timing of the latest zero point measuring to the timing of the next zero point measuring for each measuring unit on the basis of the interval between the timing of the zero point measuring immediately before and the timing of the latest zero point measuring and the variation extent of the zero point weight value from the zero point measuring immediately before until the timing of the latest zero point measuring.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a combination weigher, and more particularly to zero adjustment of a measuring instrument used in a combination weigher.

  As described in paragraph 0005 of Patent Document 1, in the combination weigher, the zero adjustment of all weighing instruments, for example, weighing hoppers equipped with load sensors, is sequentially performed at regular intervals or every certain number of times during operation. Done automatically.

JP 2012-63228 A

  During normal operation, when an article is discharged from each weighing hopper included in the combination weigher, the article is immediately supplied to the weighing hopper from a supply hopper arranged above the weighing hopper. In order to adjust the zero point, it is necessary to accurately measure the weight signal (zero point weight value) from the load sensor in the state where the article is not supplied to the weighing hopper. Therefore, when adjusting the zero point during the operation of the combination weigher, a state where no articles are supplied to the weighing hopper during the operation is forcibly created for a certain period of time, and then the load sensor of the weighing hopper is With the weight signal stabilized, the zero point weight value is acquired and the zero point is adjusted.

  Therefore, since the weighing hopper that has reached the timing for zero adjustment is empty, it cannot participate in the combination calculation, and the accuracy of the combination calculation decreases as the number of weighing hoppers participating in the combination calculation decreases, and the yield with respect to the lower limit weight value is reduced. Decreases. Therefore, from the standpoint of maintaining the combination accuracy, it is desirable to take as long an interval as possible for the zero point adjustment of each weighing hopper.

  On the other hand, if the zero adjustment interval is set too long, the zero point of the load sensor of the weighing hopper will drift greatly during that time, or a large amount of deposits will accumulate on the weighing hopper, causing the zero point weight value to fluctuate greatly. The actual quantity accuracy of the combined product obtained by the calculation is lowered. In addition, if the property of the object to be weighed changes during the operation of the combination weigher, the amount of the object to be weighed changes to the weighing hopper, and the magnitude of the zero point variation also changes. Quantity accuracy decreases. Therefore, from the standpoint of maintaining the actual quantity accuracy, it is desirable to make the interval between the zero adjustments of each weighing hopper as short as possible.

  If the zero adjustment interval is set to be short in this way, the accuracy of the weighing value of each weighing hopper can be increased.However, if the zero adjustment interval is set long to reduce the combination accuracy and maintain the combination accuracy, The quantity accuracy is lowered, and the combination accuracy and the actual quantity accuracy are in a trade-off relationship. Therefore, it is necessary to set an appropriate zero-point adjustment interval during the operation in consideration of the combination accuracy and the actual amount accuracy.

  It is an object of the present invention to provide a combination weigher that can optimally produce a combination product from both aspects of combination accuracy and actual amount accuracy.

  The combination weigher according to one aspect of the present invention includes a plurality of measuring instruments for measuring the weight of the objects to be weighed supplied by the supplying means. For example, the weighing instrument may be a weighing hopper provided with a load sensor that measures the weight of an object to be weighed supplied therein. A combination calculation means performs combination calculation of the weights of the objects to be weighed measured by the plurality of measuring instruments. An automatic zero adjustment means automatically performs zero adjustment for each of the plurality of measuring instruments. The automatic zero adjustment is performed by measuring a zero weight value that is a weight value of the measuring instrument at a zero measuring timing when the object to be weighed is not supplied to the measuring instrument in operation. For each of the plurality of measuring instruments, the automatic zero adjustment interval control means corrects the interval from the current zero measurement timing to the next zero adjustment timing. This correction is based on the interval between the previous zero measurement timing and the current zero measurement timing, and the amount of variation between the zero weight value of the previous zero measurement timing and the zero weight value of the current zero measurement timing. Done.

  Adjustment of the interval from the current zero point measurement timing to the next zero point adjustment timing includes the interval between the previous zero point measurement timing and the current zero point measurement timing, the zero point weight value of the previous zero point measurement timing, and The predetermined standard zero adjustment interval can be corrected based on the amount of change from the zero point weight value of the current zero point measurement timing.

  With this configuration, the zero adjustment interval of each measuring instrument includes the interval between the previous zero measurement timing and the current zero measurement timing, the zero weight value of the previous zero measurement timing, and the current zero measurement. Based on the amount of variation between the zero point weight value of the timing, that is, according to the zero point fluctuation rate, if the zero point fluctuation rate is large, the zero adjustment interval is shortened and the zero point fluctuation rate is small. Increases the interval of zero adjustment to achieve harmony between combination accuracy and actual quantity accuracy.

  By the way, each measuring instrument has a temperature change due to the warming up of the load sensor and measuring circuit as the number of times and time have elapsed since the start of the operation, and the weighted object is attached to the weighing hopper. The magnitude of the zero point fluctuation amount changes due to a change in the amount increase rate. Generally, the zero point fluctuation amount at the same time elapsed amount of the weighing hopper due to these factors is large in the time zone shortly after the start of the operation operation, and is small and stable as time elapses. If the zero-point adjustment interval is fixed, it is necessary to set the interval according to the zero-point fluctuation amount in the time zone shortly after the start of operation in order to prevent inaccurate weighing accuracy. Even when the operation time is long, the zero point adjustment is performed at an unnecessarily short interval, and the operation is continued for a long time in a state where the combination accuracy is lowered.

  A combination weigher according to another aspect of the present invention includes the plurality of weighing instruments, a combination calculation unit, and an automatic zero adjustment unit, and performs a predetermined number of combination selections as the amount of time elapsed from the start of operation. Or, set a predetermined elapsed time, set the number of executions of multiple selected combinations, or set the interval of automatic zero adjustment with different values corresponding to the elapsed time, and select the combination from the start of operation Counts the number of times or elapsed time, and every time they reach a predetermined value, the automatic zero adjustment of each measuring instrument is performed at an automatic zero adjustment interval with a different value set corresponding to the predetermined value In this way, the zero point is adjusted at an appropriate interval according to the state of the zero point fluctuation speed of each measuring instrument.

  That is, the automatic zero adjustment interval control means predicts in advance the zero point fluctuation speed corresponding to the passage of time after the start of the operation and obtains a plurality of different zero point execution intervals corresponding to the amount of elapsed time by the automatic zero adjustment interval setting means. Program control is performed to control the zero point adjustment execution interval according to the amount of time elapsed from the start of the operation operation while counting the amount of time elapsed during operation operation.

  The combination weigher of the above two modes is summarized as follows. In the combination weigher including the plurality of weighing units, the combination calculation unit, and the automatic zero point adjusting unit, the automatic zero point adjustment interval control unit is configured to Every time, the interval between the current zero measurement timing and the next zero measurement timing is changed from the interval between the previous zero measurement timing and the current zero measurement timing. (I wanted to keep the expression corresponding to claim 1, so I want to keep it as it is.)

  The plurality of measuring devices may be provided with a zero adjustment execution interval / zero fluctuation amount related information display means. The zero-point adjustment execution interval / zero-point variation related information display means includes an interval from the zero-point measurement timing to the current zero-point measurement timing or an amount of fluctuation of the zero-point weight value, or the interval (from the zero-point measurement timing to the current zero-point measurement timing). ) And the zero point weight fluctuation value (the fluctuation amount of the zero point weight value in the interval from the zero point measurement timing to the current zero point measurement timing) and the predetermined zero point adjustment execution interval, and the predetermined zero point adjustment execution interval. Calculate and display the zero point variation. With this configuration, the interval from the zero point measurement timing to the current zero point measurement timing or the zero point weight value fluctuation amount, and the zero point fluctuation amount at the predetermined zero point adjustment execution interval in each measuring instrument are displayed. Useful.

  Further, a zero-point fluctuation amount allowable value setting means for setting an allowable value for the zero-point fluctuation amount at the predetermined zero-point adjustment execution interval, and an alarm signal when the zero-point fluctuation amount at the predetermined zero-point adjustment execution interval exceeds the allowable value. Zero point variation warning means can also be provided. If comprised in this way, it can be known by a display whether the zero point variation | change_quantity in predetermined | prescribed zero point adjustment implementation space | interval exceeds the said allowable value, and the measuring instrument which is a zero point abnormality easily becomes clear.

  It is also possible to provide a zero point adjustment number display means for counting and displaying the number of times the zero point adjustment has been automatically performed for each of the plurality of measuring instruments. If comprised in this way, when the number of displayed zero point adjustment implementations is compared with each other, it turns out that the larger the count value, the larger the zero point fluctuation amount is on average, which is useful as maintenance information.

  As described above, according to the present invention, by controlling the zero point adjustment interval in the combination weigher based on the zero point fluctuation rate, it is possible to prevent a reduction in actual amount accuracy and a reduction in combination accuracy. .

It is a schematic block diagram of one Embodiment of the combination scale by this invention. It is a block diagram of the combination weigher of FIG. It is a block diagram of the calculation control part of the combination weigher of FIG. It is explanatory drawing of the zero point adjustment in the combination weigher of FIG. It is a block diagram of the frequency counter provided in the calculation control part of the combination weigher of FIG. FIG. 2 is a configuration diagram of a zero point adjustment execution request register and a zero point adjustment completed register provided in the calculation control unit of the combination weigher of FIG. 1. It is a flowchart which shows a part of process which the calculation control part of the combination scale of FIG. 1 performs. It is a flowchart which shows the other part of the process which the calculation control part of the combination scale of FIG. 1 performs. It is a flowchart which shows the remaining part of the process which the calculation control part of the combination scale of FIG. 1 performs.

  In the combination weigher according to one embodiment of the present invention, as shown in FIG. 1, a dispersion device 2 that disperses the object to be measured radially by vibration is provided. The dispersion device 2 includes a conical top cone 2a and a vibration source 2b that vibrates the top cone 2a. An object to be weighed (hereinafter referred to as an article) supplied on the top cone 2a is conveyed toward the peripheral edge of the top cone 2a by vibration. A plurality of, for example, ten linear feeders 4 are provided on the peripheral edge of the top cone 2. The linear feeder 4 has a trough 4a for conveying an article straightly and a vibration source 4b for vibrating the trough 4a.

  At the tip of each trough, a plurality of, for example, 10 supply hoppers 6 are arranged so as to be located on the circumference, and a measuring hopper 8a of a measuring instrument 8 is arranged below them, and further below that Ten memory hoppers 10 are arranged respectively. The supply hopper 6 is provided with a discharge gate 6a. By opening the discharge gate 6a, articles are supplied to the weighing hopper 8a below. The weighing hopper 8a is provided with a load sensor, for example, a load cell (LC) 8b, and weighs articles supplied from the supply hopper 6 above the weighing hopper 8a to generate a weight signal. The weighing hopper 8a is provided with two discharge gates 8c and 8d. By opening the discharge gate 8c, the articles in the weighing hopper 8a are supplied to the memory hopper 10 below, and the discharge gate 8d is opened, thereby weighing. The articles in the hopper 8a are discharged to the collecting chute 12. The memory hopper 10 is disposed inside the collective chute 12. The memory hopper 10 is also provided with a discharge gate 10a. By opening the discharge gate 10a, the articles inside the memory hopper 10 are discharged to the collecting chute 12.

  As shown in FIG. 2, the output of each load cell 8 b is digitized by the A / D conversion unit 14 and supplied to the arithmetic control unit 16. The arithmetic control unit 16 controls the supply hopper gate 6a, the weighing hopper gates 8c and 8d, and the memory hopper gate 10a through the gate drive unit 18, and the dispersion device vibration source 2b and the straight feeder vibration source 4b through the vibration control unit 20. Control. The arithmetic control unit 16 performs these controls based on a program stored in the storage unit 22, and the storage unit 22 is also used as a work area for these controls. An operation setting display 24 is provided in the arithmetic control unit 16 for setting data used for these controls and displaying data representing the operating state of the combination weigher. The set data includes a target weight, an allowable value for the target weight, such as an allowable upper limit weight.

  During the operation of the combination weigher, the articles are accommodated from the supply hopper 6 into the weighing hopper 8a below the supply hopper 6. The weight of the article is measured by the load cell 8b, supplied to the arithmetic control unit 16, and stored as the weight of the article in each weighing hopper 8a. The article weighed by the weighing hopper 8a is accommodated in the memory hopper 10 below the article, and the weight of the article is stored in the arithmetic control unit 16 as the weight of the article of the memory hopper 10. The empty weighing hopper 8a is supplied with articles from the supply hopper 6 thereabove and is weighed, and the weight is stored in the arithmetic control unit 16.

  A combination calculation is performed in the calculation control unit 16 for the weight of the articles stored in the weighing hopper 8a and the memory hopper 10 capable of discharging the articles directly to the collective chute 12, and the target weight is selected from the combination weights. An equal or closest combination weight is selected. If the selected combination weight is equal to or less than the allowable upper limit weight, the articles are discharged from the weighing hopper 8a and the memory hopper 10 containing the selected articles to the collecting chute 12. When the article is discharged from the memory hopper 10 and the article is present in the upper weighing hopper 8a (not included in the selected weight combination), the article is transferred from the upper weighing hopper 8a to the memory hopper 10. Are transferred to the weighing hopper 8a included in the selected combination of weights and the weighing hopper 8a to which the articles are transferred to the memory hopper 10, the articles are supplied from the upper supply hopper 6. Thereafter, the same is repeated.

  Hereinafter, the principle of the zero adjustment operation of this embodiment will be described. As the number of weight values to be combined increases, the number of combinations increases, so the probability that there is a combination weight close to the target weight increases, and the average yield of product weight values improves. Accordingly, it is necessary to supply articles from the supply hopper 6 as soon as the weighing hopper 8a is empty in order to produce articles with high yield and high processing capacity. However, since an article adheres to the weighing hopper 8a or the load cell 8b has a zero point drift, the zero point of the weight signal of the load cell 8b varies. If the zero point fluctuates, it becomes a combination selection by an incorrect weight value, and an error occurs between the weight measurement value by the combination weigher and the actual weight.

  Accordingly, during the operation of the combination weigher, each weighing instrument 8 has an interval at which the zero point of the weight signal does not drift beyond the allowable value so that the weight signal of the load cell 8b does not exceed the allowable value. It is necessary to adjust the zero point.

  When the article is discharged from the weighing hopper 8a, the weight signal vibrates, so that an accurate zero point weight value is calculated after a predetermined stabilization waiting time has elapsed from the time when the article is discharged to the weighing instrument that performs zero point adjustment. Acquired by the control unit 16. The weighing hopper 8a must wait in an empty state until the stabilization waiting time elapses. In the meantime, the combination calculation is performed on the other items of the weighing hopper 8a and the memory hopper 10. Since there is an empty weighing hopper, the number of weighing hoppers 8a to be selected for combination is reduced, so that the probability that the combination accuracy is lowered is increased.

  Therefore, when the plurality of weighing instruments 8 simultaneously adjust the zero point, the number of weighing hoppers 8a to be combined is reduced, the combination selection probability is further lowered, and the probability that the yield value of the combination weight value is increased is increased. Therefore, in this combination weigher, the zero point is adjusted by only one weighing hopper at the timing when the articles are discharged from each weighing hopper 8a.

  In the zero point adjustment, first, the standard zero point adjustment execution interval is determined as follows, for example. The operation of the load cell 8b is normal, the average condition in the normal use state, that is, a considerable energization time has passed after the combination weigher is started (not during warming up), the ambient temperature is stable, and the weighing hopper 8a is moved to. A period in which the zero point fluctuation amount when the adhesion amount of the article is an average amount is within, for example, 30% of the predetermined zero point fluctuation allowable value es is defined as the standard zero point adjustment execution interval Ps. In this embodiment, this period is represented by the number of times the combination selection is established. That is, when a certain weighing hopper 8a selects a combination for the number of times corresponding to the standard zero adjustment execution interval Ps or after that, when the selected combination is discharged, it is considered that the standard zero adjustment execution interval has elapsed. . It is also possible to directly count the elapsed time.

Assuming that this standard zero point adjustment execution interval is Ps, the relationship of the standard fluctuation amount of the zero point weight in this standard zero point adjustment execution interval is defined as the standard fluctuation rate Rs. Rs = 0.3es / Ps
It expresses.

According to an operation sequence described later, the zero point fluctuation amount in the zero point adjustment interval Px from the previous zero point adjustment timing (the zero point adjustment timing is a timing when the article is discharged from any of the weighing hoppers 8a) to the current zero point adjustment timing. When the absolute value of WDx is obtained, the zero point fluctuation rate Rx in the zero point adjustment interval Px is:
Rx = | WDx | / Px
It is obtained by Therefore, the next zero adjustment execution interval Px, which is the interval from the current zero adjustment timing to the next zero adjustment timing,
Px = k · Ps · (Rs / Rx)
And calculate.

  That is, when the current zero point fluctuation rate Rx is large, the next zero point adjustment execution interval Px is corrected to a value smaller than the standard zero point adjustment execution interval Ps, and when the current zero point fluctuation rate Rx is small, the next zero point adjustment execution interval. Px is corrected to a value larger than the standard zero point adjustment execution interval Ps. Note that k is a coefficient, and 1 is selected as a standard.

  However, if the zero point adjustment execution interval is too short, there are often empty weighing hoppers 8a, and the combination accuracy is lowered. Therefore, the allowable minimum period, that is, the minimum zero adjustment adjustment interval is set to a predetermined value, for example, Ps / 2. The zero adjustment interval is not set below this value.

  On the other hand, even if the interval is Ps / 2, if the zero point fluctuation amount reaches a predetermined allowable upper limit fluctuation amount, for example, 0.9es (90% of the allowable value es), an alarm signal is output as a zero point abnormality. Output.

  On the other hand, even if the zero point variation rate Rx is small, if the zero point adjustment execution interval is too long, an unexpected trouble may occur suddenly. Therefore, the maximum allowable period is set to a predetermined value, for example, 2Ps. For values greater than this, the zero adjustment interval is not set.

In order to output the alarm signal, a zero point fluctuation amount WDm during a predetermined zero point adjustment execution interval, for example, the minimum zero point adjustment execution interval Ps / 2, based on the current zero point fluctuation rate is calculated for each measuring instrument hopper 8a. WDm is
WDm = Rx · (Ps / 2)
It is. If this value is displayed on the operation setting display 24 every time WDm is calculated for each weighing hopper 8a, the zero point fluctuation amount of each weighing hopper 8a at the same interval can be compared, and the allowable accuracy of the zero point fluctuation amount Comparison with is also possible. In addition, an alarm signal is output because a situation in which a zero-point fluctuation amount corresponding to an allowable value occurs during the minimum zero-point adjustment execution interval Ps / 2 is abnormal. This is useful as maintenance information.

  In addition to this, the number of zero adjustments for each weighing hopper 8a is also displayed on the operation setting display 24. When the number of zero point adjustments of each weighing hopper 8a is compared at a certain point in time, it means that the larger the number of times, the larger the zero point fluctuation amount is, and this value is also useful as maintenance information.

  As shown in FIG. 3, the zero point adjustment for each load cell 8b is performed by automatic zero point adjusting means, for example, a plurality of sub arithmetic circuits 16a, provided in the arithmetic control unit 16 corresponding to each measuring instrument 8. In addition to this, the arithmetic control unit 16 has a main arithmetic circuit 16b. The main arithmetic circuit 16b includes combination arithmetic, supply hopper 8 gate 6a, weighing hopper gates 8c and 8d, memory hopper gate 10a, dispersion device vibration source 2b, straight ahead The feeder vibration source 4b is controlled.

Each sub-operation circuit 16a is supplied with an A / D conversion value Wad obtained by A / D converting the measurement signal of the corresponding load cell 8b by the A / D conversion unit 14. As the weight measurement value Wn of the article accommodated in the weighing hopper 8a, Wad is input to the sub-operation circuit 16a.
Wn = K · (Wad−Wi) −Wz
It is obtained by performing the operation. K is a span coefficient, and Wi is a tare load of the weighing hopper 8a and an initial zero point movement amount of the load cell 8b. When the article is discharged from the weighing hopper 8a and the weighing hopper 8a is empty and the discharge stabilization waiting time has elapsed, the weight value Wn is a zero point weight value. When an article adheres to the hopper 8a, it fluctuates.

  When the value of Wn + Wz is put into Wz by the zero point adjustment operation, Wn can be set to 0 when the zero point weight value Wn is not 0. This operation is zero point adjustment.

  The previous zero adjustment is performed to set Wn = 0, and after the zero adjustment adjustment interval Px, the weighing hopper 8a is emptied, and Wn measured after the discharge waiting time is the current zero weight value, and the zero fluctuation from the previous time It is also WDx.

Hereinafter, the zero adjustment operation in this combination weigher will be schematically described with reference to FIG. First, the above-described zero-point variation allowable value es and standard zero-point adjustment execution interval Ps are determined and set (not shown), and the standard variation rate Rs is calculated and stored. In consideration of the fact that the zero point fluctuation speed is generally large at the start of operation, P1 having a value smaller than the standard zero point adjustment execution interval Ps is set. If each measuring instrument 8 performs zero adjustment at the same time, the combination calculation becomes impossible. Basically, the default value of the zero adjusting timing of each measuring instrument is set so that the zero adjusting timing does not overlap between the measuring instruments 8. Determine. For example, if there are 10 measuring instruments 8 of measuring instruments 81 to 810, the zero adjustment interval p1 of each measuring instrument is set to p1 = P1 / 10,
As shown in FIG. 4, the zero point adjustment execution interval is shifted by p1 in the order of the measuring instruments 81 to 810. The number of times interval P1 is set to 1 period and 2 periods, and the goal is to cause each of the measuring instruments 81 to 810 to perform zero point adjustment twice at the interval of P1. However, when each measuring instrument reaches the zero point adjustment timing, it is not always the case that the measuring instrument is selected as a combination. To implement.

  For example, when P1 is 200, p1 is 20, and when the combination is selected 20 times after the combination is selected, the scale 81 performs zero adjustment when the combination is selected, and the measurement unit 82 selects the combination 40 times. When the combination is selected after that, the zero point adjustment is performed, and the measuring instrument 810 performs the zero point adjustment when the combination is selected 200 times after the combination is selected. This is the first period. When the weighing instrument 81 is further selected 220 times (20 (= p1) +200 (= P1)) after the combination is selected, zero adjustment is performed, and the weighing instrument 82 is selected 240 times. When the combination is selected after that, the zero point adjustment is performed, and the measuring instrument 810 performs the zero point adjustment when the combination is selected 400 times after the combination is selected.

  Then, after the zero point adjustment in the second period is performed, the weighing instrument 81 is combined with the zero point weight value when the zero point adjustment is performed after the 20th combination is established and the combination after the 220th combination is established. The zero point fluctuation amount WDx1 of the measuring instrument 81 is obtained from the difference from the zero point weight value when the zero point is selected and adjusted. After the zero point adjustment in the second period is performed, the weighing device 82 is selected as a combination after the 40th combination is established and the zero point weight value when the zero point adjustment is performed, and after the 240th combination is established. Then, the zero point fluctuation amount WDx21 of the measuring device 82 is obtained from the difference from the zero point weight value when the combination is selected and zero adjustment is performed.・ ・ ・ Weigher 810 is a combination of zero point weight value when zero point adjustment is made after the zero point adjustment is performed after the zero point adjustment is performed in the second period and after 400 times combination is established. The zero point fluctuation amount WDx10 of the measuring device 810 is obtained from the difference from the zero point weight value when the zero point is selected.

As described above, when the zero point adjustment of the measuring instrument 810 is completed in the second period, the zero point fluctuation amounts WDx1 to WDx10 of all the measuring instruments 81 to 810 are prepared, so that absolute values | WDx1 | to | WDx10 | The average variation rate Rxav of the zeros for all the measuring instruments 81 to 810 is calculated as Rxav = | WDx | av / P1 based on the average value | WDx | av and the number of times P1.
The second zero adjustment interval P2 is obtained by the following equation: P2 = k · Ps (Rs / Rxav)
Ask for. However, Rs is
Rs = 0.3es / Ps
Seeking by

  When P2 is calculated, the number interval value p2 is determined as p2 = P2 / 10. Thereafter, the zero point adjustment is performed in the same manner. Since the zero point adjustment execution interval is related to the combination accuracy, the automatic zero point adjustment of each weighing hopper 8a is currently performed during operation, or the object to be weighed adheres to the weighing hopper 8a Since it is important information for maintenance to recognize the amount of variation of the zero point for each weighing hopper 8a and the average value thereof, these values are displayed on the operation setting display 24. The zero point adjustment execution interval is determined by using the average value of the zero point fluctuation amount of each weighing hopper 8a, but may be determined based on the maximum absolute value with the fastest zero point fluctuation.

  A process performed by the arithmetic control unit 16 in order to perform the above-described zero adjustment will be described. By this processing, the arithmetic control unit functions as automatic zero adjustment interval control means. In order to perform this processing, the arithmetic control unit 16 is provided with a number counter shown in FIG. This counter corresponds to each measuring instrument 81 to 810, and includes a counter for the first period and the second period for each measuring instrument.

  That is, the counter for the first period of the measuring instrument 81 is C11, the counter for the second period is C12, the counter for the first period of the measuring instrument 82 is C21, the counter for the second period is C22,. The counter for the first period of the measuring instrument 810 is C110, and the counter for the second period is C210. When the combination weigher is started, p1 is stored in C11, p1 + 10p1 is stored in C12, 2p1 is stored in C21, 2p1 + 10p1 is stored in C22, 10p1 is stored in C110, and 10p1 + 10p1 is stored in C210. Basically, the count value is decremented by 1 every time the combination is selected.

  The arithmetic control unit 16 is also provided with an execution request register shown in FIG. This is also provided for each weighing instrument 81 to 810 for one period and two periods, the articles in the weighing hopper are discharged in the weighing instruments 81 to 810, and then the load signal is stabilized and the zero point can be adjusted. Then, if the zero point adjustment is possible in the first period, 1 is set as a sign bit in the register of the first period of the measuring instrument, and if the zero point adjustment is possible in the second period, , 1 is set as a sign bit in the register of the second period of the measuring instrument.

  The arithmetic control unit 16 is also provided with a zero-adjusted register shown in FIG. This is also provided for each of the measuring instruments 81 to 810 for one period and for two periods. When the zero point adjustment has been performed, if the zero point adjustment has been performed in the first period, If 1 is set as the sign bit in the register of the first period and the zero point adjustment has been performed for the second period, 1 is set as the sign bit in the register of the second period of the measuring instrument.

  As shown in FIG. 7, the main circuit 16b of the arithmetic control unit 16 first sets the above-described default values in the number counter as shown at the start of operation in FIG. 5 (step S2). Next, it is determined whether or not the combination weigher is stopped (step S4). If the answer to this determination is yes, step S4 is repeated until the answer to the determination is no.

  If the answer to this determination is no, it is determined whether it is the timing for reading the weight value of each measuring instrument 8 (step S6). If the answer to this determination is yes, the weight value of each measuring instrument 8 is read (step S8). Next, a combination calculation is performed to determine whether the combination selection has been established (step S10).

  If the answer to the determination in step S10 is yes, all count values are decremented by 1 (step S12). For example, in the previous example, when combination selection is established for the first time after the start of operation, the value of the counter C11 in the first period of the measuring instrument 81 is 20 to 19, and the value of the counter C21 in the second period is 210 to 209, the value of the counter C12 in the first period of the measuring instrument 82 is 40 to 39, the value of the counter C22 in the second period of the measuring instrument 82 is 240 to 239, and so on. The value of the counter C110 in the first period is from 200 to 199, and the value of the counter C210 in the second period is from 400 to 399. If the counter content is already 0 or F, which will be described later, -1 is not performed.

  Next, it is determined whether or not any of the number counters has reached 0 (step S14). If the answer to this determination is yes, the sign bit of the meter for which the value of the number counter has become 0 and the zero adjustment execution request register for the period is set to 1, and F is set to the number counter that has reached 0. (Step S16). At this point, it is determined by checking the contents of the zero point adjustment execution request register which zero meter can be adjusted. The reason why F is set in the number counter is to prevent the number counter value from being read twice.

  For example, in the above example, when the combination selection is established 20 times from the start of operation, the counter C11 for the first period corresponding to the measuring instrument 81 becomes 0, so the first measuring instrument 81 in the zero adjustment execution request register. 1 is set as a sign bit in the area corresponding to the period, and F is set in the counter C11.

  Next, as shown in FIG. 8, it is determined whether there is a measuring instrument to be zero-adjusted (step S18). This is done by determining whether there is one of the zero adjustment execution request registers. If the answer to this determination is yes, it is determined whether or not the zero adjustment operation can be performed (step S20). That is, it is determined whether or not a measuring instrument having a zero adjustment execution request register set to 1 is selected.

  If the answer to this determination is yes, the corresponding meter and period sign bit in the zero adjustment execution request register are reset (step S22), the corresponding meter and period sign bit in the zero adjusted register are set to 1. (Step S24). For example, in the above example, the area corresponding to the first period of the measuring instrument 81 in the zero adjustment adjustment request register is reset, and 1 is set in the area corresponding to the first period of the measuring instrument 81 in the zero adjustment completed register. Set as a sign bit.

  Then, execution of zero adjustment is instructed to the sub-operation circuit 16a corresponding to the measuring instrument in which the sign bit of the zero adjustment completed register is 1 (step S26). Note that there may be several measuring instruments with the sign bit set to 1 in the zero-adjusted register at the same time. In this case, basically, the measuring instrument number is small and the zero-adjustment interval is small. Priority is given to zero adjustment. For example, if the sign bits in the areas corresponding to the measuring instruments 81 and 83 in the zero-adjusted register are simultaneously 1, the measuring instrument 81 is preferentially adjusted to zero.

  Subsequent to step S26 or if the answer to the determination in step S6, S10 or S14 is no, it is determined whether there is an output of the zero point weight from the sub-operation circuit 16a (step S28). If the answer to this determination is no, the process is executed again from step S4.

  If the answer to the determination in step S28 is yes, as shown in FIG. 9, the zero point weight value is read, and the zero point weight value for each measuring instrument and for each period is stored (step S30). Then, in the measuring instrument in which both the zero point weight values in the first period and the second period are obtained, the zero point fluctuation amount is calculated as the zero point weight value in the second period−the zero point weight value in the first period ( Step S32).

  Following step S32, it is determined whether all of the current zero adjustments have been completed for all measuring instruments (step S34). For example, the first time and the second time shown in FIG. 4 are each a first period and a second period, and the zero point adjustment is performed twice for all the measuring instruments 8. Say.

  If the answer to this determination is no, the process is executed again from step S4 in FIG. If the answer to this determination is yes, the zero-point-adjusted registers for the first period and the second period are reset, and the next period Px is calculated as described above. An eye zero adjustment execution interval px is calculated and set in the number counter (step S36).

  For example, if it is the second time, P2 is calculated as Px, the zero point adjustment execution interval p2 is calculated based on this, and the counters C11, C21, C21, C22,. .. p2, p2 + 10p2, 2p2, 2p2 + 10p2,... 10p2, 10p2 + 10p2 are set in C110 and C210. Although the allowable minimum interval is set to Ps / 2 and the allowable maximum interval is set to 2Ps, the illustration is omitted. However, when Px calculated as described above is equal to or smaller than the allowable minimum interval, the value of P2 is set to Ps / 2. However, if the allowable maximum interval is 2Ps or more, the value is set to 2Ps.

  Then, a new zero point adjustment execution interval Px is displayed on the operation setting display 24, and the zero point fluctuation amount for each weighing hopper calculated in step S32 and the average value of these zero point fluctuation amounts are displayed (step S38). Execute again from step S4.

  Although not shown, the zero point fluctuation amount WDm based on the zero point fluctuation rate calculated when determining the next zero point adjustment execution interval Px is calculated for each of the measuring instruments 81 to 810, and each time WDm is calculated. And displayed on the operation setting display 24. That is, the operation setting display 24 and the main arithmetic circuit 16b function as a zero adjustment execution interval / zero fluctuation amount related information display means. The zero point fluctuation amount WDm can be calculated in step S38, or can be calculated every time the zero point fluctuation amount is calculated in step S32.

  When the zero-point fluctuation amount WDm is calculated, the WDm is compared with a predetermined allowable value, and when a zero-point fluctuation amount exceeding the allowable value is generated, an alarm signal is output and the fact is displayed on the operation setting display unit 24. . That is, the operation setting display 24 and the main arithmetic circuit 16b also function as a zero point fluctuation amount alarm means.

  A counter for counting the number of zero point adjustments is provided in the main arithmetic circuit 16b corresponding to each of the measuring instruments 81 to 810. When the zero weight value of the corresponding measuring instrument is read from the sub operation circuit 16a, it is determined that the zero has been adjusted, the count value is incremented by 1, and the value of each counter is displayed on the operation setting display unit 24. That is, the operation setting display 24 and the main arithmetic circuit 16b also function as zero point adjustment number display means.

  In the above embodiment, the number of the measuring instruments 8 is ten. However, the number of measuring instruments 8 is not limited to this, and can be arbitrarily increased or decreased. In the above embodiment, the memory hopper 10 is provided, but it may be removed depending on circumstances. In the above embodiment, the next zero adjustment execution interval Px is calculated and corrected as Px = k · Ps (Rs / Rx). However, the present embodiment is not limited to this, and the current zero-point variation rate Rx is greater than Rs. When it is larger, the next zero adjustment execution interval is made smaller than the current zero adjustment execution interval Px by a predetermined value Pa, and when the current zero point fluctuation rate Rx is smaller than Rs, the next zero adjustment execution interval Px is predetermined. The value Pa may be corrected to a value larger than the current zero point adjustment execution interval Px.

  As another embodiment, the program control of the zero point adjustment execution interval can be performed as follows, for example. Similar to the above embodiment, the amount of time elapsed after the start of the operation operation is counted as the number of times of combination selection, and the zero adjustment interval from the start of the operation operation is the amount of time elapsed from the start of the operation operation. T1 when the combination selection count reaches 0, T2 when reaching T1, T3 when reaching T1 + T2, T4 after reaching T1 + T2 + T3, T1 <T2 <T3 <T4, and the main arithmetic circuit 16a It is set in the provided automatic zero adjustment interval setting means. When the amount of elapsed time reaches T4, the zero point adjustment is repeated at a constant value of the execution interval T4 until the operation ends.

  After the start of operation, start at the number of executions T1, and adjust the zero point of each measuring instrument in the same way as in FIG. 4, count the number of combination selections, compare with the set value T1, and at the time when it matches T1, the next execution The interval T2 is called, and the second time is performed with the set value T2. Then, when the number of combination selections reaches T1 + T2, the next execution interval T3 is called, the third time is performed with the set value T3, and the fourth time after the time when the number of combination selections reaches T1 + T2 + T3 is performed with the set value T4. .

  In the embodiment described above, the execution interval of the next zero adjustment is newly calculated according to the magnitude of the zero variation actually appearing at the end of each time, whereas the predetermined number of times is completed. At this point, the next preset number of times is used, which is different from this embodiment.

  In each measuring instrument, every time the fluctuation amount of the zero point weight value is obtained at the zero point measurement timing, the zero point fluctuation amount from the previous zero point measurement timing to the current zero point measurement timing, and a predetermined interval therebetween. By calculating and displaying the amount of zero fluctuation per hit, the operator can easily grasp the difference in the zero fluctuation of each measuring instrument according to the elapsed time from the start of operation. Program settings can be made.

  Although the zero point adjustment execution interval is set to T1 to T4, the zero point adjustment execution interval can be set to T3 after the time when the number of combination selections reaches T1 + T2, for example, as T1 to T3. The adjustment execution interval may be T1 to T5, and may be performed at the installation value T4 when the combination selection count reaches T1 + T2 + T3, and after the time when the combination selection count reaches T1 + T2 + T34, the adjustment interval may be performed at the execution interval T5. Also, for example, T3> T4 can be set depending on the difference in the magnitude of the zero point variation with the lapse of the operation time of each weighing hopper.

8 Meter 16 Calculation control unit (Combination calculation means, automatic zero adjustment means, automatic zero adjustment interval control means)

Claims (6)

A plurality of weighing devices for weighing the objects to be weighed supplied by the supply means;
A combination calculation means for performing a combination calculation of the weights of the objects measured by the plurality of weighing devices;
For each of the weighing instruments, zero adjustment is automatically performed by measuring the zero weight value, which is the weight value of the weighing instrument at the zero measurement timing when the weighing object is not supplied to the weighing instrument in operation. Automatic zero adjustment means for performing
During operation, automatic zero adjustment that changes the interval from the current zero measurement timing to the next zero measurement timing for each of the measuring instruments is different from the interval between the previous zero measurement timing and the current zero measurement timing. An interval control means,
A combination weigher.   2. The combination weigher according to claim 1, wherein the automatic zero-adjustment interval control means is configured so that, during the operation, the interval between the previous zero-measurement timing and the current zero-measurement timing, and the zero-point weight of the previous zero-measurement timing. A combination weigher that corrects the interval from the current zero measurement timing to the next zero measurement timing based on the amount of change between the current value and the zero weight value of the current zero measurement timing.   2. The combination scale according to claim 1, wherein the automatic zero adjustment interval control means sets a plurality of intervals from the current zero measurement timing to the next zero measurement timing in advance corresponding to the amount of time elapsed from the start of operation. An automatic zero adjustment interval setting means, and based on the elapsed time from the start of the operation and the interval corresponding to the elapsed time set in the automatic zero adjustment interval setting means, the current zero measurement A combination weigher that corrects the interval from the timing to the next zero measurement timing.   2. The combination weigher according to claim 1, wherein an interval from the previous zero point measurement timing to the current zero point measurement timing or a fluctuation amount of the zero point weight value, or the interval, a fluctuation amount of the zero point weight value, and a predetermined zero point adjustment execution interval, A combination scale equipped with a zero point adjustment execution interval / zero point fluctuation amount related information display means for calculating and displaying a zero point fluctuation amount at the predetermined zero adjustment execution interval calculated based on   5. The combination weigher according to claim 4, wherein zero-point fluctuation amount allowable value setting means for setting an allowable value for the zero-point fluctuation amount in the predetermined zero-point adjustment execution interval, and the zero-point fluctuation amount in the predetermined zero-point adjustment execution interval exceeds the allowable value. A combination weigher comprising zero point fluctuation amount alarm means for outputting an alarm signal.   6. The combination weigher according to claim 1, further comprising a zero point adjustment number display means for counting and displaying the number of times the zero point adjustment has been automatically performed for each of the weighing instruments.

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